1. Field of the Invention
The present invention relates to a photographic film cassette. More particularly, the present invention relates to a photographic film cassette in which a leader of photographic film is entirely contained in a cassette shell prior to use, and rotation of a spool causes the leader to advance to the outside of the cassette shell.
2. Description of the Related Art
In a conventional photographic film cassette containing 135 photographic film, a photographic film leader protrudes to the outside of a cassette shell even before use of the photographic film. To load a camera with such a cassette, a user is required to pay attention the cassette shell as well as the protruded leader. It has been proposed to construct a cassette in which not only a roll of film but also a leader thereof is contained in a cassette shell, and rotation of a spool causes the leader to advance to the outside of the cassette shell, as disclosed in U.S. Pat. Nos. 4,832,275 and 4,834,306 and a commonly assigned U.S. Pat. No. 5,213,277. It is also known, as disclosed in a commonly assigned European Patent Publication NO. EP-A2 0 406 815, to use an openable cover member for preventing light from entering the inside of the cassette shell through a passage port for the photographic film.
Presently, external apparatuses for use with the photographic film, such as a photographic film processor, a photographic film video player, are adapted to loading with the entirety of the photographic film being contained in the cassette. It is conceivable to load a wrong apparatus with the cassette, e.g., load the video player with a cassette containing unexposed photographic film, or load the processor with a cassette containing the developed photographic film. Therefore, when a cassette contains the photographic film of any status, e.g., unexposed, exposed and developed, prevention of errors during handling is a problem, because the status of the photographic film cannot be recognized externally.
U.S. Pat. No. 4,965,600, in view of such a situation, discloses a photographic film cassette, and a camera for use with the same, in which a status of photographic film in the cassette is indicated externally as one of being Completely Unexposed, Partly Exposed or Completely Exposed.
The openable cover member disclosed in European Patent Publication No. EP-A2 0 406 815, does not reliably provide protection against ambient light. Such an openable cover member is supported on the cassette shell via a hinged structure, and thus the cover member could be accidentally opened when subjected to shock or vibration even to a small extent, e.g., in the course of use or transportation.
The construction in U.S. Pat. No. 4,965,600 also has a problem in that the camera to be used with the cassette must incorporate a complicated arrangement inclusive of a device for opening/closing the cover member, a device for driving the indication for the status of the photographic film, a device for driving the spool, and a double exposure preventive device for avoiding loading of the cassette which contains the exposed photographic film. This does not render it useful with a compact camera because the relevant devices require a sufficiently large dimension of the camera. Also, the devices are expensive to manufacture.